JP2015152324A - Substrate treating apparatus, and method of detecting edge chipping of substrates - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate treating apparatus provided with an edge chipping detector that can detect any edge chipping of substrates.SOLUTION: A substrate treating apparatus is equipped with substrate carrying mechanisms 6, 12 and 77 that carry a substrate W to polishing units 3A to 3D, an edge chipping detector 40 and cleaning units 73 and 74 in this order. The edge chipping detector 40 has a plurality of ultrasonic sensors 42 that sense edges of the substrate W and a sensor output monitoring unit 45 that determines whether or not at least one of the output signals of the plurality of ultrasonic sensors 42 has reached a prescribed threshold.

Description

  The present invention relates to a substrate processing apparatus that processes a substrate such as a wafer, and more particularly, to a substrate processing apparatus having a function of detecting an edge defect of a substrate. The present invention also relates to a method for detecting a chipped edge of a substrate.

  In recent years, as semiconductor devices are highly integrated, circuit wiring is becoming finer and the distance between wirings is becoming narrower. In particular, in the case of optical lithography with a line width of 0.5 μm or less, the depth of focus becomes shallow, so that the flatness of the imaging surface of the stepper is required. As one means for flattening the surface of a substrate such as a wafer, a substrate processing apparatus that performs chemical mechanical polishing (CMP) is known.

  The substrate processing apparatus includes a polishing unit for polishing the surface of a wafer. The polishing unit includes a polishing table to which a polishing pad that constitutes a polishing surface is attached, and a top ring that holds a wafer. Each of the polishing table and the top ring is configured to be rotatable. A polishing liquid (slurry) is supplied onto the polishing pad while rotating the polishing table and the top ring. In this state, the wafer is polished in a state where the polishing liquid exists between the wafer and the polishing pad by pressing the wafer against the polishing pad with the top ring. The polished wafer is transferred to the cleaning unit by the transfer mechanism, and the wafer polished by the cleaning unit is cleaned and dried.

  In the polishing unit, when the polished wafer is pulled up from the polishing pad or when the wafer is released from the top ring, the edge (periphery) of the wafer may be chipped. The transfer mechanism described above is equipped with an optical sensor that detects whether or not a wafer is present on the wafer transfer stage, but as long as the optical axis of this optical sensor does not pass through the portion lacking the wafer edge, Such edge chipping of the wafer cannot be detected.

  If the chipped wafer is transported to the cleaning unit, the wafer may be broken into pieces when the wafer is cleaned by the cleaning unit. If the wafer breaks into pieces, wafer debris adheres to a cleaning tool such as a roll sponge arranged in the cleaning unit, and damages the cleaning tool. Furthermore, the cleaning tool needs to be replaced, and the running cost of the substrate processing apparatus increases.

  In addition, if the wafer is cleaned using a cleaning tool with fragments attached, not only the wafer is contaminated but also the wafer is scratched. Therefore, if the wafer breaks into pieces, the operation of the substrate processing apparatus is stopped, and the inside of the substrate processing apparatus is sufficiently cleaned so that all the wafer fragments scattered in the substrate processing apparatus can be collected. Need arises. However, such cleaning takes a very long time and increases the downtime of the substrate processing apparatus.

JP 2010-50436 A

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a substrate processing apparatus including an edge defect detection unit that can detect an edge defect of a substrate such as a wafer. Another object of the present invention is to provide a method for detecting an edge defect in a substrate.

  One aspect of the present invention includes a polishing unit that polishes a substrate, a cleaning unit that cleans the polished substrate, an edge chip detection unit that detects an edge chip of the substrate, the substrate, the polishing unit, An edge chipping detection unit, and a substrate transport mechanism that transports the cleaning unit to the cleaning unit in this order, and the edge chipping detection unit includes a plurality of ultrasonic sensors that detect edges of the substrate, and a plurality of ultrasonic sensors. A substrate processing apparatus comprising: a sensor output monitoring unit that determines whether or not at least one of the output signals has reached a predetermined threshold value.

In a preferred aspect of the present invention, the plurality of ultrasonic sensors are arranged above the substrate held by the substrate transport mechanism.
In a preferred aspect of the present invention, the plurality of ultrasonic sensors are arranged along an edge of the substrate held by the substrate transport mechanism.
In a preferred aspect of the present invention, each of the plurality of ultrasonic sensors is a distance sensor that measures a distance between two points.
In a preferred aspect of the present invention, each of the plurality of ultrasonic sensors emits an ultrasonic wave toward the edge of the substrate, receives the reflected ultrasonic wave, and changes in accordance with a time difference between transmission and reception of the ultrasonic wave. Is output.
A preferable aspect of the present invention further includes an operation control unit that controls operations of the polishing unit, the cleaning unit, and the substrate transport mechanism, and the edge chipping detection unit determines that the edge of the substrate is chipped The operation control unit stops operations of the polishing unit and the substrate transport mechanism.
In a preferred aspect of the present invention, the predetermined threshold value is an ultrasonic sensor when a distance between an outer edge of an effective spot of ultrasonic waves emitted from the ultrasonic sensor and an edge of the substrate is a predetermined distance. It is a value of the output signal of.

  In another aspect of the present invention, the edge of the substrate is sensed by a plurality of ultrasonic sensors, and it is determined whether at least one of the output signals of the plurality of ultrasonic sensors has reached a predetermined threshold value. This is a method for detecting an edge defect of a substrate.

  According to the present invention, it is possible to detect an edge defect of a substrate by comparing output signals of a plurality of ultrasonic sensors with a predetermined threshold value. In addition, since the edge chip is detected before the substrate is transported to the cleaning unit, the substrate is prevented from being broken into pieces by the cleaning unit.

It is a top view which shows the substrate processing apparatus which concerns on one Embodiment of this invention. It is a perspective view which shows a 1st grinding | polishing unit typically. It is a perspective view which shows the structure of a swing transporter. It is the perspective view which showed the ultrasonic sensor arrange | positioned above the wafer hold | gripped by the swing transporter. It is the schematic side view which showed the positional relationship of an ultrasonic sensor and a board | substrate. FIG. 6A is a schematic diagram showing the positional relationship between the effective spot of the ultrasonic wave and the edge of the substrate when the substrate is not chipped, and FIG. 6B is a schematic diagram when the substrate is chipped. It is the schematic which showed the positional relationship of the effective spot of a sound wave, and the edge of a board | substrate. It is the graph which showed the output signal of the ultrasonic sensor which changes according to the change of the distance of the outer edge of the effective spot of an ultrasonic wave, and the edge of a board | substrate.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a plan view showing a configuration of a substrate processing apparatus according to an embodiment of the present invention. This substrate processing apparatus is a composite apparatus capable of polishing, cleaning and drying a substrate such as a wafer. As shown in FIG. 1, the substrate processing apparatus includes a rectangular housing 1, and the inside of the housing 1 is divided into a load / unload unit 2, a polishing unit 3, and a cleaning unit 4 by partition walls 1a and 1b. Has been. The substrate processing apparatus has an operation control unit 5 that controls a wafer processing operation.

  The load / unload unit 2 includes a front load unit 20 on which a substrate cassette for stocking a large number of wafers (substrates) is placed. A traveling mechanism 21 is laid along the front load section 20 in the load / unload section 2, and a transport robot (loader) 22 that can move along the arrangement direction of the substrate cassettes on the traveling mechanism 21. Is installed. The transfer robot 22 can access the substrate cassette mounted on the front load unit 20 by moving on the traveling mechanism 21.

  The polishing unit 3 is an area where a wafer is polished. The polishing unit 3 includes a first polishing unit 3A, a second polishing unit 3B, a third polishing unit 3C, and a fourth polishing unit 3D. As shown in FIG. 1, the first polishing unit 3A includes a first polishing table 30A to which a polishing pad 10 having a polishing surface is attached, and holds the wafer and presses the wafer against the polishing pad 10 on the polishing table 30A. The first top ring 31A for polishing while polishing, the first polishing liquid supply nozzle 32A for supplying a polishing liquid (for example, slurry) or a dressing liquid (for example, pure water) to the polishing pad 10, and polishing of the polishing pad 10 A first dresser 33A for performing dressing of the surface, and a first atomizer 34A for spraying a mixed fluid of a liquid (for example, pure water) and a gas (for example, nitrogen gas) in the form of a mist onto the polishing surface.

  Similarly, the second polishing unit 3B includes a second polishing table 30B to which the polishing pad 10 is attached, a second top ring 31B, a second polishing liquid supply nozzle 32B, a second dresser 33B, and a second atomizer 34B. The third polishing unit 3C includes a third polishing table 30C to which the polishing pad 10 is attached, a third top ring 31C, a third polishing liquid supply nozzle 32C, a third dresser 33C, The fourth atomizing unit 3D, the fourth polishing unit 3D includes a fourth polishing table 30D to which the polishing pad 10 is attached, a fourth top ring 31D, a fourth polishing liquid supply nozzle 32D, and a fourth polishing liquid supply nozzle 32D. A dresser 33D and a fourth atomizer 34D are provided.

  Since the first polishing unit 3A, the second polishing unit 3B, the third polishing unit 3C, and the fourth polishing unit 3D have the same configuration, the first polishing unit 3A will be described below with reference to FIG. I will explain. FIG. 2 is a perspective view schematically showing the first polishing unit 3A. In FIG. 2, the dresser 33A and the atomizer 34A are omitted.

  The polishing table 30A is connected to a table motor 19 disposed below the table shaft 30a, and the table motor 19 rotates the polishing table 30A in the direction indicated by the arrow. A polishing pad 10 is affixed to the upper surface of the polishing table 30A, and the upper surface of the polishing pad 10 constitutes a polishing surface 10a for polishing the wafer W. The top ring 31 </ b> A is connected to the lower end of the top ring shaft 16. The top ring 31A is configured to hold the wafer W on the lower surface thereof by vacuum suction. The top ring shaft 16 is moved up and down by a vertical movement mechanism (not shown).

  The polishing of the wafer W is performed as follows. The top ring 31A and the polishing table 30A are rotated in directions indicated by arrows, respectively, and a polishing liquid (slurry) is supplied onto the polishing pad 10 from the polishing liquid supply nozzle 32A. In this state, the top ring 31 </ b> A presses the wafer W against the polishing surface 10 a of the polishing pad 10. The surface of the wafer W is polished by the mechanical action of abrasive grains contained in the polishing liquid and the chemical action of the polishing liquid. After the polishing is completed, dressing (conditioning) of the polishing surface 10a is performed by the dresser 33A (see FIG. 1), and a high-pressure fluid is further supplied from the atomizer 34A (see FIG. 1) to the polishing surface 10a to the polishing surface 10a. Residual polishing scraps and abrasive grains are removed.

  Returning to FIG. 1, a first linear transporter 6 is disposed adjacent to the first polishing unit 3A and the second polishing unit 3B. The first linear transporter 6 is a mechanism for transferring a wafer between four transfer positions (first transfer position TP1, second transfer position TP2, third transfer position TP3, and fourth transfer position TP4). Further, the second linear transporter 7 is disposed adjacent to the third polishing unit 3C and the fourth polishing unit 3D. The second linear transporter 7 is a mechanism for transporting a wafer between three transport positions (fifth transport position TP5, sixth transport position TP6, and seventh transport position TP7).

  The wafer is transferred to the polishing units 3A and 3B by the first linear transporter 6. The top ring 31A of the first polishing unit 3A moves between the upper position of the polishing table 30A and the second transport position TP2 by the swing operation. Accordingly, the wafer is transferred between the top ring 31A and the first linear transporter 6 at the second transfer position TP2.

  Similarly, the top ring 31B of the second polishing unit 3B moves between the upper position of the polishing table 30B and the third transfer position TP3, and the wafer is transferred between the top ring 31B and the first linear transporter 6. Is performed at the third transfer position TP3. The top ring 31C of the third polishing unit 3C moves between the upper position of the polishing table 30C and the sixth transfer position TP6, and wafer transfer between the top ring 31C and the second linear transporter 7 is the sixth. This is performed at the transfer position TP6. The top ring 31D of the fourth polishing unit 3D moves between the upper position of the polishing table 30D and the seventh transfer position TP7, and wafer transfer between the top ring 31D and the second linear transporter 7 is the seventh. This is performed at the transfer position TP7.

  The wafer delivery mechanism between the polishing units is not limited to the above-described example. For example, the wafer may be transferred by moving the top ring directly to another polishing unit while holding the wafer. The wafer may be polished by all four polishing units 3A to 3D, or by one or more of the polishing units 3A to 3D (for example, the first polishing unit 3A and the second polishing unit 3B). It may be polished.

  A lifter 11 for receiving a wafer from the transfer robot 22 is disposed adjacent to the first transfer position TP1. The wafer is transferred from the transfer robot 22 to the first linear transporter 6 through the lifter 11. A shutter (not shown) is provided between the lifter 11 and the transfer robot 22 in the partition wall 1a. When the wafer is transferred, the shutter is opened so that the wafer is transferred from the transfer robot 22 to the lifter 11. It has become.

  A swing transporter 12 is disposed between the first linear transporter 6, the second linear transporter 7, and the cleaning unit 4. Wafer transport from the first linear transporter 6 to the second linear transporter 7 is performed by the swing transporter 12. The wafer is transferred to the third polishing unit 3C and / or the fourth polishing unit 3D by the second linear transporter 7.

  A wafer buffer stage 72 installed on a frame (not shown) is disposed on the side of the swing transporter 12. As shown in FIG. 1, the buffer stage 72 is disposed adjacent to the first linear transporter 6, and is located between the first linear transporter 6 and the cleaning unit 4. The swing transporter 12 transports the wafer between the fourth transport position TP4, the fifth transport position TP5, and the buffer stage 72.

  The wafer W polished by the polishing units 3A and 3B is transferred to the fourth transfer position TP4 by the first linear transporter 6. Further, the wafer W is transferred by the swing transporter 12 from the fourth transfer position TP4 to an edge defect detection position (described later) above the fifth transfer position TP5, and the edge of the wafer W is detected at the edge defect detection position. Chip detection is performed. The wafer W polished by the polishing units 3C and 3D is transferred to the fifth transfer position TP5 by the second linear transporter 7. Further, the wafer W is transferred by the swing transporter 12 to the edge defect detection position above the fifth transfer position TP5, and edge defect detection of the wafer W is performed at this edge defect detection position.

  After edge missing detection is performed, the wafer is placed on the buffer stage 72 by the swing transporter 12. The wafer on the buffer stage 72 is transferred to the cleaning unit 4 by the first transfer robot 77 of the cleaning unit 4. As shown in FIG. 1, the cleaning unit 4 is cleaned with a first cleaning unit 73 and a second cleaning unit 74 that clean the polished wafer using a cleaning liquid, a roll sponge (not shown), or the like. And a drying unit 75 for drying the wafer. The first transfer robot 77 operates to transfer the wafer from the buffer stage 72 to the first cleaning unit 73 and to transfer the wafer from the first cleaning unit 73 to the second cleaning unit 74. A second transfer robot 78 is arranged between the second cleaning unit 74 and the drying unit 75. The second transfer robot 78 operates to transfer the wafer from the second cleaning unit 74 to the drying unit 75.

  FIG. 3 is a perspective view showing the structure of the swing transporter 12 according to one embodiment of the present invention. The swing transporter 12 is installed on the frame 100 of the substrate processing apparatus, and extends as a linear guide 101 extending in the vertical direction, a swing mechanism 102 attached to the linear guide 101, and a drive source for moving the swing mechanism 102 in the vertical direction. And an elevating drive mechanism 105. As the elevating drive mechanism 105, a ROBO Cylinder having a servo motor and a ball screw can be employed. A reversing mechanism 107 is connected to the swing mechanism 102 via a swing arm 106. Further, a gripping mechanism 110 that grips the wafer W is connected to the reversing mechanism 107.

  The swing arm 106 is configured to turn around the rotation axis of the motor by driving a motor (not shown) of the swing mechanism 102. As a result, the reversing mechanism 107 and the gripping mechanism 110 rotate integrally, and the gripping mechanism 110 moves between the fourth transport position TP4, the fifth transport position TP5, and the buffer stage 72.

  The gripping mechanism 110 has a pair of gripping arms 111 that grip the wafer W. At both ends of each gripping arm 111, chucks 112 that grip the edge of the wafer W (that is, the peripheral edge of the wafer W) are provided. These chucks 112 are provided so as to protrude downward from both ends of the gripping arm 111. Further, the gripping mechanism 110 includes an opening / closing mechanism 113 that moves the pair of gripping arms 111 in a direction to approach and separate from the wafer W.

  The wafer W is gripped as follows. With the gripping arm 111 open, the gripping mechanism 110 is lowered by the lift drive mechanism 105 until the chuck 112 of the gripping arm 111 is positioned in the same plane as the wafer W. Then, the opening / closing mechanism 113 is driven to move the gripping arms 111 in directions close to each other, and the edge of the wafer W is gripped by the chuck 112 of the gripping arms 111. In this state, the lifting / lowering drive mechanism 105 raises the grip arm 111.

  The reversing mechanism 107 includes a rotating shaft 108 coupled to the gripping mechanism 110 and a rotary actuator (not shown) that rotates the rotating shaft 108. As the rotary actuator, a fluid pressure type rotary actuator that operates with a fluid pressure such as air pressure can be adopted. Instead of the fluid pressure type rotary actuator, a motor drive type rotary actuator provided with a motor for rotating the rotating shaft 108 may be used. When the rotary shaft 108 is driven by the rotary actuator, the entire gripping mechanism 110 is rotated by 180 degrees, whereby the wafer W gripped by the gripping mechanism 110 is reversed.

  The holding mechanism 110 moves to the buffer stage 72 while holding the wafer W, and opens the holding arm 111 to place the wafer W on the buffer stage 72. The wafer W placed on the buffer stage 72 is transferred to the cleaning unit 4 by the first transfer robot 77 of the cleaning unit 4. In the substrate processing apparatus of this embodiment, the wafer W is transferred to the polishing unit 3, the linear transporters 6 and / or 7, the swing transporter 12, the buffer stage 72, and the cleaning unit 4 in this order.

  In the polishing unit 3A shown in FIG. 2, when the polished wafer W is pulled up from the polishing pad 10 or when the wafer W is released from the top ring 31A at the transfer position, a part of the wafer W is broken and the wafer is broken. W edges may be missing. Therefore, as shown in FIG. 3, the substrate processing apparatus according to the present embodiment is provided with an edge defect detection unit 40 for detecting an edge defect of the wafer. Hereinafter, the edge defect detection unit 40 will be described.

  As illustrated in FIG. 3, the edge defect detection unit 40 includes a plurality of (eight in the illustrated example) ultrasonic sensors 42. These ultrasonic sensors 42 are disposed above the fifth transport position TP5 (that is, above the second linear transporter 7). The polished wafer W is reversed by the swing transporter 12 and conveyed to a predetermined edge defect detection position. This edge missing detection position is located below the ultrasonic sensor 42 and above the fifth transport position TP5.

  FIG. 4 is a perspective view showing the ultrasonic sensor 42 disposed above the wafer W held by the swing transporter 12. In FIG. 4, a state in which the wafer W is inverted by the swing transporter 12 is illustrated. The wafer W is transferred to the edge chipping detection unit 40 by the gripping mechanism 110 of the swing transporter 12.

  As shown in FIG. 4, the plurality of ultrasonic sensors 42 are disposed above the wafer W inverted by the swing transporter 12. Since the wafer W transferred to the edge chipping detection unit 40 is a wafer immediately after being polished, a polishing liquid is attached to the wafer W. As shown in FIGS. 3 and 4, the ultrasonic sensor 42 is disposed above the wafer W held by the swing transporter 12, so that the polishing liquid falls from the wafer W onto the ultrasonic sensor 42. There is no. Further, the polishing liquid adhering to the wafer W is shaken off by the reversing operation of the wafer W by the swing transporter 12. Therefore, failure and abnormal operation of the ultrasonic sensor 42 due to the polishing liquid can be prevented.

  The ultrasonic sensors 42 are arranged at equal intervals along the edge of the wafer W held by the swing transporter 12. These ultrasonic sensors 42 are fixed to an annular sensor holding base 43. The sensor holding base 43 is fixed to a bracket (not shown). Each of the ultrasonic sensors 42 is connected to a sensor output monitoring unit 45 included in the edge missing detection unit 40. The sensor output monitoring unit 45 may be built in the operation control unit 5 that controls the wafer processing operation (see FIG. 1), or may be configured separately from the operation control unit 5.

  Each ultrasonic sensor 42 is configured to sense the edge of the wafer W. More specifically, the ultrasonic sensor 42 emits an ultrasonic wave from the top of the wafer W toward the edge, receives an ultrasonic wave reflected from the wafer W (and an object existing around the wafer W), A signal that changes according to the time difference between the transmission and reception of a sound wave is output. The ultrasonic sensor 42 of the present embodiment having such a configuration is a reflective ultrasonic sensor in which the ultrasonic sensor itself transmits and receives ultrasonic waves, and is a distance sensor that measures the distance between two points. used. The ultrasonic sensor 42 is configured to transmit the output signal to the sensor output monitoring unit 45.

  FIG. 5 is a schematic side view showing the positional relationship between the ultrasonic sensor 42 and the wafer (substrate) W. FIG. As shown in FIG. 5, the distance between the ultrasonic sensor 42 and the wafer W when detecting a chipped edge of the wafer W is, for example, 100 mm. In this case, the effective spot diameter of the ultrasonic wave in the same plane as the surface of the wafer W is, for example, 40 mm. The ultrasonic effective spot is an ultrasonic circular area in which the ultrasonic sensor 42 can effectively measure the distance between the ultrasonic sensor 42 itself and the object, and the effective spot diameter is a diameter of the circular area.

  The ultrasonic sensor 42 used as a distance sensor has a feature that the output signal of the ultrasonic sensor 42 increases as the object moves away from the effective spot. The edge defect detection unit 40 detects an edge defect of the wafer W based on such a change in the output signal of the ultrasonic sensor 42. As shown in FIG. 5, the ultrasonic sensor 42 is arranged so that the outer edge of the effective spot of ultrasonic waves is in contact with the edge of the wafer W. The position of the ultrasonic sensor 42 shown in FIG. 5 is a predetermined position of the ultrasonic sensor 42 for sensing the edge of the wafer W.

  FIG. 6A is a schematic diagram showing the positional relationship between the ultrasonic effective spot and the edge of the wafer W when the wafer W is not chipped. FIG. 6B is a diagram illustrating the wafer W chipped. FIG. 5 is a schematic diagram showing a positional relationship between an effective spot of ultrasonic waves and an edge of a wafer W in the case. As shown in FIG. 6A, when the wafer W is not chipped, the distance between the outer edge of the effective ultrasonic spot and the edge of the wafer W is zero. On the other hand, as shown in FIG. 6B, when the wafer W is missing, the distance between the outer edge of the ultrasonic effective spot and the edge of the wafer W is greater than zero. The distance between the outer edge of the effective ultrasonic spot and the edge of the wafer W varies according to the size of the edge defect of the wafer W.

  FIG. 7 is a graph showing an output signal of the ultrasonic sensor that changes in accordance with a change in the distance between the outer edge of the ultrasonic effective spot and the edge of the wafer W. In FIG. 7, the vertical axis represents the output signal of the ultrasonic sensor 42, and the horizontal axis represents the distance between the outer edge of the effective ultrasonic spot and the edge of the wafer W. When the wafer W is not chipped as shown in FIG. 6A (that is, when the distance between the outer edge of the ultrasonic effective spot and the edge of the wafer W is 0 mm), the output signal of the ultrasonic sensor 42 is P1. It is. When the wafer W is missing as shown in FIG. 6B (that is, when the distance between the outer edge of the effective ultrasonic spot and the edge of the wafer W is greater than 0 mm), the output signal of the ultrasonic sensor 42 is P2 (> P1). When the wafer W is largely missing or when the wafer W itself does not exist, the output signal of the ultrasonic sensor 42 is constant at a certain value P3 (> P2).

  As can be seen from FIG. 7, the output signal of the ultrasonic sensor 42 increases according to the size of the edge defect of the wafer W (that is, the distance between the outer edge of the ultrasonic effective spot and the edge of the wafer W). When the edge defect becomes large to some extent, the output signal of the ultrasonic sensor 42 becomes constant at a certain value.

  In the present embodiment, a predetermined threshold value is provided for the output signal of the ultrasonic sensor 42. This predetermined threshold value is the value of the output signal of the ultrasonic sensor 42 when the distance between the outer edge of the effective spot of ultrasonic waves emitted from the ultrasonic sensor 42 and the edge of the wafer W is a predetermined distance. . This threshold value is set in the sensor output monitoring unit 45. The sensor output monitoring unit 45 monitors the output signals of the plurality of ultrasonic sensors 42, determines whether at least one of the output signals of the plurality of ultrasonic sensors 42 has reached this threshold value, and at least When one output signal reaches the threshold value, it is determined that the wafer W has an edge defect.

  The threshold value of the output signal of the ultrasonic sensor 42 in the present embodiment is the value of the output signal of the ultrasonic sensor 42 when the distance between the outer edge of the effective ultrasonic spot and the edge of the wafer W is 3 mm. It is set (see FIG. 7). This is because the notch (V-shaped notch) for confirming the reference direction of the wafer W has a size of 2 mm. By setting the threshold value to the value of the output signal corresponding to the distance of 3 mm, it is possible to prevent the ultrasonic sensor 42 from erroneously determining that the notch is an edge defect of the wafer W. Thus, according to the present embodiment, the size of the edge defect to be detected can be determined by the threshold value. More than eight ultrasonic sensors 42 may be provided in order to increase the detection accuracy of the edge defect of the wafer W.

  Chipping of the wafer edge is likely to occur in the polishing units 3A to 3D. When a chipped wafer (that is, a wafer that is partially missing) is cleaned by the cleaning unit 4, the wafer may be shattered. Therefore, it is preferable to detect an edge defect of the wafer before the wafer is transferred to the cleaning unit 4. For this reason, the wafer W is transferred in the order of the polishing unit 3A (and 3B to 3D), the edge chip detection unit 40, and the cleaning units 73 and 74. In the present embodiment, the substrate transport mechanism that transports the wafers W in this order includes the first linear transporter 6 (and the second linear transporter 7), the swing transporter 12, and the first transport robot 77. . The ultrasonic sensor 42 of the edge chip detection unit 40 is disposed between the polishing units 3 </ b> A to 3 </ b> D and the cleaning units 73 and 74.

  In the present embodiment, the ultrasonic sensor 42 is disposed above the fifth transport position TP5, but the ultrasonic sensor 42 may be installed in another location. For example, the ultrasonic sensor 42 may be installed above the buffer stage 72 or the first linear transporter 6.

  When the edge chip detection unit 40 detects the edge chip of the wafer, the operation control unit 5 includes the polishing units 3A to 3D and the substrate transport mechanism (first linear transporter 6, second linear transporter 7, swing transporter 12, And the operation of the first transfer robot 77) is stopped. The worker removes the wafer with the missing edge from the substrate processing apparatus, and this prevents the wafer with the missing edge from being conveyed to the cleaning unit 4. After the wafer is removed from the substrate processing apparatus, the operation of the substrate processing apparatus is resumed.

  When the edge chip detection unit 40 detects the edge chip of the wafer, the swing transporter 12 places the chip on the buffer stage 72 shown in FIG. 1, and then the operation control unit 5 performs the polishing units 3A to 3D. In addition, the operation of the substrate transfer mechanism may be stopped. In addition, a second buffer stage (not shown) on which the wafer is temporarily placed is provided separately from the buffer stage 72 which is the first buffer stage, and the wafer lacking the edge is placed on the second buffer stage. Later, the operation control unit 5 may stop the operations of the polishing units 3A to 3D and the substrate transport mechanism. After the chipped wafer is placed on the second buffer stage, the operations of the polishing units 3A to 3D and the substrate transport mechanism can be continued as they are. For example, the second buffer stage can be disposed above or below the first cleaning unit 73 or the second cleaning unit 74 disposed in the cleaning unit 4.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea described in the claims and the specification and drawings. Is possible.

DESCRIPTION OF SYMBOLS 1 Housing 2 Load / unload part 3 Polishing part 3A, 3B, 3C, 3D Polishing unit 4 Cleaning part 5 Operation control part 6 1st linear transporter 7 2nd linear transporter 10 Polishing pad 11 Lifter 12 Swing transporter 16 Top Ring shaft 19 Table motor 20 Front load part 21 Traveling mechanism 22 Transport robot 30A, 30B, 30C, 30D Polishing table 31A, 31B, 31C, 31D Top ring 32A, 32B, 32C, 32D Polishing liquid supply nozzle 33A, 33B, 33C, 33D Dresser 34A, 34B, 34C, 34D Atomizer 40 Edge missing detector 42 Ultrasonic sensor 43 Sensor holding base 45 Sensor output monitor 72 Buffer stage 73 First cleaning unit 74 Second cleaning unit G 75 Drying unit 77 First transfer robot 78 Second transfer robot 100 Frame 101 Linear guide 102 Swing mechanism 105 Lifting drive mechanism 106 Swing arm 107 Reversing mechanism 108 Rotating shaft 110 Grip mechanism 111 Grip arm 112 Chuck 113 Open / close mechanism

Claims (8)

A polishing unit for polishing a substrate;
A cleaning unit for cleaning the polished substrate;
An edge chip detection unit for detecting an edge chip of the substrate;
A substrate transport mechanism for transporting the substrate to the polishing unit, the edge chipping detection unit, and the cleaning unit in this order;
The edge defect detection unit is
A plurality of ultrasonic sensors for sensing an edge of the substrate;
A substrate processing apparatus, comprising: a sensor output monitoring unit that determines whether at least one of output signals of the plurality of ultrasonic sensors reaches a predetermined threshold value.   The substrate processing apparatus according to claim 1, wherein the plurality of ultrasonic sensors are disposed above the substrate held by the substrate transport mechanism.   The substrate processing apparatus according to claim 1, wherein the plurality of ultrasonic sensors are arranged along an edge of the substrate held by the substrate transport mechanism.   The substrate processing apparatus according to claim 1, wherein each of the plurality of ultrasonic sensors is a distance sensor that measures a distance between two points.   Each of the plurality of ultrasonic sensors is configured to emit an ultrasonic wave toward the edge of the substrate, receive the reflected ultrasonic wave, and output a signal that changes according to a time difference between the transmission and reception of the ultrasonic wave. The substrate processing apparatus according to claim 4, wherein the substrate processing apparatus is provided. An operation control unit for controlling operations of the polishing unit, the cleaning unit, and the substrate transport mechanism;
The operation control unit stops the operations of the polishing unit and the substrate transport mechanism when the edge chip detection unit determines that the edge of the substrate is chipped. Substrate processing equipment.   The predetermined threshold is a value of an output signal of the ultrasonic sensor when a distance between an outer edge of an effective spot of ultrasonic waves emitted from the ultrasonic sensor and an edge of the substrate is a predetermined distance. The substrate processing apparatus according to claim 1. Detecting the edge of the substrate with multiple ultrasonic sensors,
A method for detecting an edge defect of a substrate, comprising: determining whether at least one of output signals of the plurality of ultrasonic sensors has reached a predetermined threshold value.

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